Mill classifier

Abstract

The invention relates to a mill classifier or sifter, particularly a roller mill classifier, which is suitable as a high-performance classifier for a roller pan mill or a roller mill, e.g. for an air-swept mill. In order to achieve in the case of a particularly simple construction a high flexibility and optimization of the classifying processes as a function of the particular needs, there is a combination of a static distributor formed from several adjustable guide blade rings and a ledge rotor as the dynamic classifier. In order to achieve a multiple classifying and in particular a reduction of the coarse material fraction prior to dynamic classifying, in the vicinity of the static distributor is provided a deflecting device in an area of the classifier cover, through which the disadvantageous effects of a 90° deflection are largely avoided.

What is claimed is: 
     
       1. A roller mill classifier, comprising a static classifier, a dynamic classifier, and an annular classifying zone formed between said two classifiers and a deflecting device through which a fluid-grinding material flow rises and is directed through an angle greater than 120° to form a downward flow, the static classifier comprising a radially outwardly positioned guide apparatus with at least one lower guide blade ring and an upper guide blade ring, the dynamic classifier comprising a ledge rotor, wherein the lower guide blade ring and the upper guide blade ring comprise shafts arranged coaxially with one another, and wherein the deflecting device is disposed above the ledge rotor in an area adjacent to the upper guide blade ring, wherein the deflected fluid-grinding material flow forms the downward flow by action of gravity wherein the guide blade rings adjustable independently of one another and wherein a radial or tangential adjustment can be carried out individually or simultaneously for guide blades of a guide blade ring. 
     
     
       2. Mill classifier according to claim 1, wherein the guide blade rings are arranged in axially superimposed and adjustable manner and are fixed with a roughly vertically oriented fixing spindle in a vicinity of the deflecting device, which is located on a classifier cover. 
     
     
       3. Mill classifier according to claim 2, wherein the deflecting device is constructed in a marginal area of the classifier cover with a curvature having a clearly defined inclination and with a clearly defined attack angle and deflection angle and wherein a guide blade rings are arranged in the centre of curvature of the classifier cover. 
     
     
       4. Mill classifier according to claim 3, wherein the curvature is in cross-section concave, semicircular or in a form of an isosceles trapezoid with a downwardly directed opening. 
     
     
       5. Mill classifier according to claim 4, wherein a height of the curvature corresponds to roughly half a height of the upper guide blade ring. 
     
     
       6. Mill classifier according to claim 2, wherein the guide blade rings are adjustable independently of one another or jointly and wherein a radial or tangential adjustment can be carried out individually or simultaneously for all the guide blades of a guide blade ring. 
     
     
       7. Mill classifier according to claim 1, wherein for adjusting the guide blade rings adjusting levers are provided, which are in each case connected to a hollow shaft of the guide blades of the upper guide blade ring and to a solid shaft of guide blades of the lower guide blade ring, the solid shaft being guided in the hollow shaft. 
     
     
       8. Mill classifier according to claim 1, wherein below the guide blade rings is provided a partition tapering conically in a direction of a grinding zone and which in a vicinity of a ledge rotor bounds the classifying zone and terminates in an oversize material discharge opening in a vicinity of grinding rolls of the roller mill. 
     
     
       9. Mill classifier according to claim 8, wherein the partition and the classifier and mill casing form an annular zone, which tapers in a direction of a rising fluid-grinding material flow. 
     
     
       10. Mill classifier according to claim 8, wherein a central drop tube is provided for grinding material charging which extends to close to the oversize material discharge opening. 
     
     
       11. A roller mill classifier, comprising a static classifier, a dynamic classifier, an annular classifying zone formed between said classifiers, and a deflecting device through which a fluid-grinding material flow rises and is directed through an angle greater than 120° to form a downward flow, the static classifier comprising a radially outwardly positioned guide apparatus with at least one lower guide blade ring and an upper guide blade ring, the dynamic classifier comprising a ledge rotor, the upper and lower guide blade rings having shafts arranged coaxially to one another, and wherein the deflecting device is disposed above the ledge rotor in an area adjacent to the upper guide blade ring wherein the deflected fluid-grinding material flow forms the downward flow by action of gravity; wherein the upper and lower guide blade rings are arranged in axially superimposed and independently adjustable manner and are fixed with a substantially vertically oriented fixing spindle in a vicinity of the deflecting device which is located on a classifier cover; and   wherein the deflecting device is constructed in a marginal area of the classifier cover with a curvature having a clearly defined inclination and with a clearly defined attack angle and deflection angle and wherein the guide blade rings are arranged in a centre of curvature of the classifier cover.   
     
     
       12. A roller mill classifier, comprising a static classifier, a dynamic classifier, and a deflecting device through which a fluid-grinding material flow rises and is directed through an angle greater than 120° to form a downward flow and an annular classifying zone formed between said classifiers, the static classifier comprising a radially outwardly positioned guide apparatus with at least one lower guide blade ring and an upper guide blade ring, the dynamic classifier comprising a ledge rotor, the upper and lower guide blade rings having shafts arranged coaxially with one another, and wherein the deflecting device is disposed above the ledge rotor in an area adjacent to the upper guide blade ring wherein the deflected fluid-grinding material flow forms the downward flow by action of gravity; wherein the guide blade rings are arranged in axially superimposed and independently adjustable manner and are fixed with a substantially vertically oriented fixing spindle in a vicinity of the deflecting device which is located on a classifier cover;   wherein the deflecting device is constructed in a marginal area of the classifier cover with a curvature having a clearly defined inclination and with a clearly defined attack angle and deflection angle and wherein the guide blade rings are arranged in a centre of curvature of the classifier cover;   wherein the curvature is in cross-section concave, semicircular or shaped as an isosceles trapezoid with a downwardly directed opening; and   wherein the height of the curvature corresponds to substantially half the height of the upper guide blade ring.